textproduct: Rapid City

KEY MESSAGES

- Light rain will increase in coverage today across much of western South Dakota, especially east of the Black Hills. Snow may mix in with rain, especially in/near the Black Hills.

- A trace to an inch of snow is possible over northwestern South Dakota and the Black Hills through this evening.

- Warming trend commences Tuesday through the end of the week with highs in the 50s to 60s.

UPDATE

Issued at 945 PM MDT Sun Oct 25 2026

03z surface analysis had high over south-central Canada with well established upslope easterly component to boundary layer flow over the CWA. Lots of stratus/some fog as a result. Water vapour loop depicted upper low over southwestern WY with initial impulse over western SD. Rain (mostly) has waned some as impulse moves north/northeast, but main wave moves into the CWA Monday morning with better QG-forcing/synoptic lift. Should see increase in QPF late tonight, spreading through the CWA Monday. Evidence of this already in progress with cooling cloud tops over eastern WY/CO and an increase in regional radar loop returns. 00z KUNR and forecast sounding support some snow over the higher elevations of the Black Hills and potentially on the plains. Recent warm weather and diurnal cycle Monday suggest little/no snow accumulation on roadways. There is an off chance a few elevated surfaces could get icy for rural areas. Next wave arrives Monday night/Tuesday with downslope westerly low level flow/drying, although a few showers may occur ahead of the wave before we dry out.

Going forecast tweaked for latest thoughts and (much earlier in the evening) to add fog given sustained upslope flow.

DISCUSSION

(This Afternoon Through Saturday) Issued at 1146 AM MDT Sun Oct 25 2026

Rain showers have begun to push into the region this morning as upper low over the southwestern US moves northeastward. Large scale Q-vector convergence and moisture advection will continue to support this precip through the overnight hours into Monday. In terms of what kind of precip is going to fall, the majority will be rain. However, as the colder air associated with the upper low pushes into the region, we could see a rain/snow mix on portions of the western SD plains and a transition to snow over the Black Hills by late Monday morning. Snow will likely be falling during the afternoon hours when sfc temps will be in the mid 30s and even though the thermal profiles will support snow, they'll still be a tad warm. All of this means that we likely won't see much aside from some minor, slushy accumulations (generally around a trace to maybe an inch) that should melt quickly on the warm ground.

Upper level shortwave and attendant moisture starved front will move in from the PNW later on Tuesday. Could see some light rain showers across far northeastern WY into northwestern SD with this system with the only other impacts expected being breezy southwest winds across the western SD plains and portions of northeastern WY late Tuesday afternoon. Otherwise, upper level west- southwesterly flow will keep temperatures seasonably mild after Tuesday with dry weather expected through the late week.

AVIATION

(For the 12Z TAFS Through 12Z Tuesday Morning) Issued At 538 AM MDT Mon Oct 26 2026

The world of aviation is...well...extremely MOIST today, especially across western South Dakota, resulting in some significant impacts. Widespread drizzle, rain, BR/fog, and low clouds are present along with localized snow mixing in, with IFR to LIFR cigs and MVFR to IFR vsbys common. A more organized area of rain (vs. dominant ongoing drizzle) is pushing northward out of Nebraska into the region early this morning, and will continue through 23-02z/5-8pm this evening depending on location (mostly east of the Black Hills per CAMs). NBM guidance leans quite pessimistic with respect to cigs/vsbys today while some other model guidance tries to gradually SLIGHTLY improve things with time, but with no major changes in wind or airmass and the additional rain (moisture) moving in, hard to envision we'll see significant improvement through sunset, and this is reflected in the KRAP TAF. We're closely watching upstream sfc observations to calibrate and trend our forecast as we go forward and monitor things. Low stratus and some BR is likely to linger tonight as well, although a slight increase in winds may help keep fog at bay. Overall forecast confidence throughout the period is moderate. Meanwhile, current MVFR conditions at KGCC (cigs) will trend back to VFR by midday as clouds lift and break up, and vsby issues are not currently expected as the surface is just a bit drier out that way. Look for increasingly gusty SSE winds there as we head into tonight.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.